High Rise Buildings:
Recording the response of buildings during strong earthquake shaking is a key element in improving seismic design. Recorded data is valuable to assist post earthquake structural evaluation and form an important complement to data from regular networks. Lessons learned from post earthquake data are reviewed to improve the success in future events.

In various cities and counties in the United States, high rise buildings are required to have (3) working Accelerographs in the building. The instruments shall be located in the basement, midportion, and near the top of each building. Maintenance and service of the instruments shall be provided by the owner of the building, subject to the approval of the building official. Data produced by the instruments shall be made available to the building official on request. Maintenance and service of the instruments need to be provided annually by an approved testing agency. Seismic Systems provides, installs and services accelerograph equipment in high rise buildings across the United States. We can arrange qualified installation, maintenance, and training anywhere in the United States.

• What is Structural Health Monitoring?
Structural Health Monitoring (or SHM) is an innovative method of monitoring structural safety, integrity and performance without otherwise affecting the structure itself. SHM utilises several types of sensors – embedded in, or attached to – a structure to detect the presence, location, severity and consequence of damage.

• Why Structural Health Monitoring?
Let’s consider some existing structures such as buildings, bridges, tunnels, high-rise constructions, historical monuments and railways.
Unsatisfactory inspection can lead to problems that only become apparent when structures are in critical need of repair. The strength and serviceability of the structure can be considerably – even terminally – reduced by natural or human-made events, earthquakes, increased levels of use and design changes.

The result is that repair costs become comparable with replacement costs. The emerging use of SHM that we are witnessing is a result of the increasing need for the monitoring of innovative designs and materials as well as a better management of existing structures. This is further enhanced by the ongoing development and sophistication of sensors, data acquisition systems, wireless and internet technologies and other advances in technology.

In the past we have seen catastrophic structural failures such as the famous collapse of the Tacoma Bridge in 1940, (Tacoma, WA, USA); the collapse of the Historical Archive of the City of Cologne, (Germany), in 2009, or the tragic 1995 Sampoong Department Store collapse in Seoul, (South Korea). Events such as these drastically show how vulnerable infrastructure can be if exposed to conditions like wind (Tacoma), ground deformation (Cologne) or overload (Seoul). These very factors that eventually lead to failure can be measured with Geosig instruments, as well as their force, severity and effect on the structure. This not only reduces risks and costs, but also avoids disaster through early damage detection and therefore saves lives as well as the structure.

• What are the advantages of Structural Health Monitoring?
The ideal SHM system provides you with on-demand information about your structure's integrity and serviceability, as well as warnings concerning any damage detected. Therefore SHM significantly reduces repair costs through early damage detection, making the monitored structure safer and increasing the cost efficiency of its maintenance.

Structural Monitoring can significantly reduce insurance premiums for those operating - or in charge of - the safety of infrastructure such as bridges, railways or tunnels.

Other advantages of SHM include:
• increased understanding of in-situ structural behaviour
• assurance of structural strength and serviceability
• decreased down-time for inspection and repair
• development of rational maintenance/management strategies and
• an increased effectiveness in allocation of scarce resources.

Additionally SHM enables and encourages the reliable use of new and innovative materials and designs in both architecture and engineering.

Methodology & Technology

• How does Structural Health Monitoring work?

Each structure is unique, therefore the monitoring system that must be applied is also singular. In close cooperation with the contractor, GeoSIG delivers tailor-made SHM systems for each project. Trigger levels for issuing warning signals (when previously defined values are exceeded) will be set according to its particular properties and capabilities, with reference to design, resistance, durability and stability.

Various types of sensors are attached to - or embedded in - the structure itself. These devices collect raw data (accelerations, deformation/strain, temperature, moisture levels, acoustic emission, and loads among others) and transfer it to a Data Acquisition System (DAS). From the DAS, the data is collected and sampled. It is then transmitted to an offsite location for automatic, intelligent processing. This level of remote monitoring eliminates the need for site visits. The goal is to remove mundane data, noise, thermal, or other unwanted effects before storage, and to make data interpretation easier, faster and more accurate. Diagnostics convert abstract data signals into useful information about the structural response and condition.

This detailed physical data analysis can be then used to enable rational, knowledge-based engineering decisions.

In essence, SHM’s variety of measurement techniques and data interpretation create “intelligent structures” that are safer, long-lasting, more secure, and cheaper to operate, maintain and insure.